The present invention relates to a thin-film magnetic read head device comprising an end face extending in a first direction, in which a magnetic information carrier is movable with respect to the magnetic head device, and in a second direction, perpendicular to said first direction, the magnetic head device further comprising a multilayer structure with at least two soft-magnetic layers separated by a magnetic insulation layer and with at least one exchange biasing layer cooperating with one of said soft-magnetic layers, which multilayer structure extends in the second direction and in a third direction, perpendicular to the first and the second direction, and forms at least one flux path in the first and the third direction.
Such a thin-film magnetic read head device is known from Koshkawa et al, Flux-Guided MR Head for Very Low Flying Height, IEEE Trans. Magn. 30 (1994), pp. 3840-3842. In this article, particularly on page 3840 and FIG. 2, a shielded read head is described and illustrated with an interrupted wing-like exchange biasing layer, the interruption determining the read width. The wing-like embodiment of the exchange biasing layer is applied for stabilizing a magnetoresistive element by boundary control stabilization and for determining the read width. As a consequence of the structuring, i.e. the interruption, of the exchange biasing layer, this magnetic read head device is not appropriate to realize read widths below about 1 .mu.m.
In former yoke-type magnetic read heads, the dimension in the second direction of the flux guide in front of a magnetoresistive element usually determined the read width. A multichannel magnetic read head device was obtained by an arrangement in the second direction of flux guides and magnetoresistive elements cooperating therewith. However, for read widths below about 20 .mu.m, multidomain states were likely to occur in the front flux guide, resulting in Barkhausen noise. Therefore an improvement was proposed in EP application No. 96203031.8.
In order to obtain a multichannel magnetic read head device, this document describes a number of flux-guiding elements and a number of magnetoresistive elements, cooperating with said flux-guiding elements, which elements form a number of parallel flux paths in the first and the third direction, the number corresponding to the number of magnetic channels of the magnetic read head device. A channel separation, i.e. a separation of the parallel flux paths, is obtained by a magnetically anisotropic structure, the magnetic permeability thereof in the second direction being small in comparison with the magnetic permeability in the third direction.
By application of the embodiments, described in EP application No. 96203031.8, the read widths are controlled by the anisotropy in combination with the distance between the contacts on the magnetoresistive elements. This method allows use of front flux guides with a width larger than the read width and thereby retains a single domain configuration also for smaller track widths. This is a viable method for track widths down to about 5 .mu.m. For track widths of a few microns and less, this method appears to be no longer sufficient due to limitations in the soft-magnetic material properties.
In shielded magnetic read heads with the magnetoresistive elements extending to the head surface, the read width was determined by the spacing between the contacts on the magnetoresistive element or, in the case of a multichannel head, magnetoresistive elements. By careful structuring of the metallization layer and the biasing layers in the shielded heads read widths down to about 1 .mu.m could be obtained. However, structuring methods based on optical lithography will probably not have a sufficient accuracy for read widths below this value.